It is frequently necessary to make repairs to ruptured or leaking high-pressure pipes in areas of extreme explosion or fire hazard, such as the engine rooms of ships or refineries. Typical repairs consist of replacing a defective section of pipe with a new section either by directly welding the new section in place or by bolting expansion joints between welded flanges at both ends of the new section and welded flanges at the open ends of the pipeline where the damaged section was removed. In either case, on-site welding is necessary, and the areas to be worked must be freed of all flammable gases and liquids. For welding operations in new ships or new refineries, it is usually neither difficult nor costly to comply with this mandate. However, the process of "gas freeing" the engine room of an operating ship or a particular sector of a refinery is normally a costly and lengthy process.
It would be highly advantageous to be able to effect the reliable flanging or coupling of large-diameter, high-pressure pipes without the use of heat or flame. Flexible couplings for joining plain-end tubes or pipes are available from several manufacturers. Typically, these couplings comprise a tubular housing into which a tube or pipe is inserted at either end. Circular resilient seals are then clamped to seal the gaps between the housing and the tubes or pipes. Although a joint made with this type of coupling lacks the reliability and durability of a welded joint or an expansion joint between two welded flanges, it does have the advantage of simplicity of installation without the use of heat or flame.
A search made by the applicant for prior art related to the invention has revealed numerous pipe fittings and connectors. U.S. Pat. No. 2,011,433, issued to Gabriel E. Blagg on Mar. 25, 1933 teaches the construction of a pipe coupling especially useful for joining sections of thin-wall tubing. Although complementary frusto-conical surfaces are used to secure a tight joint without the use of gaskets or packing, the joint necessarily reduces the inside diameter of the line and also deforms the ends of the sections of tubing to be joined. U.S. Pat. Nos. 1,821,863 and 1,821,865, both issued to Wylie G. Wilson on Sept. 1, 1931, teach the use of a tapered seal to provide fluid-tight joints. However the method requires that the ends of the pipes to be joined be fitted with specially-designed flanges, which presumably must be welded to the ends of the pipes. U.S. Pat. No. 3,749,426, issued to Cassius Tillman on July 31, 1973, teaches the use of a pipe joint seal in the form of a tubular member having beveled ends, which is compressed between the recesses of aligned flanged pipes connected together under stressed conditions, such as with bolts, studs or clamps. Once again, however, the special flange must be welded to the ends of the pipes to be joined. There is a very real commercial need for a pipe fitting which can be tightly secured to the end of a rigid-wall, high-pressure pipe so that it may be flanged or coupled without the use of welding.